Transmission structure of woodworking lathe

A transmission structure of a woodworking lathe comprising:

• a case including a transmission shaft, a variable speed shaft, and a driven shaft, the transmission shaft being actuated by a motor, the driven shaft being configured to drive a chuck of the woodworking lathe;
• a transmission gear mounted on the transmission shaft;
• a driven gear fixed on an end of the variable speed shaft and meshing with the transmission gear;
• a first gear set connected on the driven shaft and comprised of a first gear and a third gear which is coaxial with the first gear, and diameters of the first gear and the third gear being different;
• a second gear set disposed on the variable speed shaft and comprised of a second gear and a fourth gear, a diameter of the second gear corresponding to a diameter of the first gear, a diameter of the fourth gear corresponding to a diameter of the third gear, and the second gear and the fourth gear being connected on an end of the variable speed shaft adjacent to the first gear set;
• and
• an adjustment lever defined between the second gear and the fourth gear so that the second gear set moves leftward or rightward in three speed varying sections to control the second gear to or not to mesh with the first gear or to control the fourth gear to mesh with the third gear.